Tuan,
The ‘clear overrides’ option is not shown for that AP because the system recognizes that there are no custom (override) settings that have been made to that AP that are different than the AP Profile.
If you make a manual change to an individual AP (NOT a change to the AP Profile), then that change is considered an override (it overrides the setting that exist in the AP Profile - for example, you give an AP a custom hostname or static IP address).
And any time you create override settings on individual APs, WiNG will then show the clear overrides icon. If you then use the icon to clear the overrides, WiNG will then remove those custom settings that you applied to the AP.
